So-called "radiators" are heat exchangers that are used to reject heat from the coolant of an internal combustion engine to the ambient. In a typical case, engine coolant is circulated through coolant passages in the engine block to the so-called liquid side of the radiator where it is cooled and then returned to the engine block. Cooling occurs by forcing ambient air through the radiator core as, for example, by a fan driven either by an electric motor or by a power take-off from the internal combustion engine itself.
In the usual case, the coolant systems are mildly pressurized to, for example, 7-16 psig. As a result, the coolant may heat to a temperature above its boiling point at atmospheric pressure without actually vaporizing. In this way, the wall temperature of the combustion chamber of the internal combustion engine may be maintained at a fairly constant value which is selected to maximize thermal efficiency of the engine while assuring that undue thinning of the lubricant film on relatively moving parts will not occur.
As elementary thermodynamics will demonstrate, the thermal efficiency of an engine increases as its operating temperature is increased. Consequently, it is desirable to raise the operating temperature of the engine as much as possible to maximize efficiency. If, however, the operating temperature is raised to the point where coolant within cooling passages in the engine begins to vaporize, pockets of vapor will develop and because the heat capacity of vapor usually is much less than the heat capacity of the liquid coolant, those parts of the engine contacted by the vapor will heat to undesirably high temperatures while adjacent parts contacted by liquid coolant will not. The resulting "hot spots" are undesirable from two standpoints. First, the "hot spot" may not be able to sustain an adequate lubrication film, resulting in poor lubrication and undue wear. Secondly, the temperature differential between the "hot spot" and other parts of the engine may ultimately result in damage to engine parts as, for example, warpage of reciprocating engine heads. Consequently, if engines are to be operated at higher temperatures, it is necessary that the boiling point of the coolant being employed be raised.
This, of course, can be done by increasing system pressure. For example, an increase in maximum system pressure from approximately 8 psig to 63 psig would increase the boiling point of a coolant such as water some 70 degrees fahrenheit.
At the same time, it becomes necessary to increase the strength of the radiator so that the same may operate at the increased pressure.
The present invention is directed to providing an improved high pressure resistant radiator.